WIFSS research on E. coli O157:H7 in central coastal California Rob Atwill, D.V.M., Ph.D. University of California-Davis
To all cooperators: ranchers, growers, regulators, environmentalists, resource managers, and the public THANK YOU!
Juxtaposition of plant agriculture and grazed rangeland Salinas Valley Produce Fields raw food Rangeland cow-calf & stockers wildlife habitat Chaparral wildlife habitat Salinas River riparian corridors wildlife habitat
Are these produce outbreaks the result of livestock grazing on rangeland and/or wildlife?
Minimizing pathogen movement from livestock & wildlife to food and water Livestock production & wildlife Water quality Produce food safety
Minimizing pathogen movement from livestock & wildlife to food and water Livestock production & wildlife Water quality Produce food safety
Waterborne pathogen BMPs for grazing Key processes driving waterborne contamination 1. animal loading (who done it) 2. microbial transport (how did it get there) 3. microbial inactivation (is it still alive)
Waterborne pathogen BMPs for grazing Key processes driving waterborne contamination 1. animal loading (who done it) 2. microbial transport (how did it get there) 3. microbial inactivation (is it still alive)
Sierra Foothill Research & Extension Center, University of California Buffer width (m) 0.1, 1.1, 2.1 Land slope (%) 5, 20, 35 RDM (kg/ha) 225, 560, 900, 4500
Rangeland buffers can retain 95% of key pathogens in winter and spring; >99.9% achievable under certain conditions
2012 technical reports on waterborne pathogens and BMPs, both are FREE! NRCS, USDA World Health Organization
Minimizing pathogen movement from livestock & wildlife to food and water Livestock production & wildlife Water quality Produce food safety
Testing raw product (lettuce) throughout Salinas Valley April 2008 through Nov 2011 0/2462 E. coli O157:H7 Samples taken all over Salinas Valley
Are livestock and wildlife infected with key food safety pathogens? E. coli O157:H7 in central California wildlife and cow-calf operations E. coli O157:H7, 2008-10 Feral pig 10/200 (5%) Coyote 2/95 (2%) Am. crow 5/93 (5%) Cowbird 2/60 (3%) Rabbit 0/108 (0%) Skunk 0/63 (0%) Tule elk 3/150 (2%) Deer 0/447 (0%) Cow-calf herds 68/2715 (2.5%)
Cow-calf herds, 2008-2010 E. coli O157 infection ranged from 0% to 10% Salmonella was <1% Herd pos n prev (%) A 0 489 0.0 B 7 480 1.5 C 0 200 0.0 D 44 434 10.1 E 0 61 0.0 F 6 386 1.6 G 2 271 0.7 H 9 256 3.5 I 0 138 0.0 Total 68 2715 2.5 Would vaccination for E. coli O157:H7 make sense?
Prevalence of pathogens in wild rodents in produce production fields, central California 0.2% infected with E. coli O157:H7 no difference b/t produce or livestock sites 3% infected with Salmonella areas with high trap success (>20%) Rodent species Cryptosporidium Giardia CA parasitic mouse 11% 13% Deer mouse 33% 27% Dusky-footed wood rat 17% 17% Total 28% 25% Preliminary data: Crypto appears human infectious, Giardia mostly not
2011 & 2012 field trials of romaine lettuce, Salinas Valley
Add in 2 hours of irrigation 20 to 30% heads of lettuce contaminated with E. coli O157:H7
E. coli O157:H7 / head lettuce E. coli O157:H7 per head of Romaine lettuce 1,000,000 10,000 100 1 0 10 15 20 25 Distance between lettuce and scat (inches)
E. coli O157:H7 / head lettuce 100,000 E. coli O157:H7 per head of Romaine lettuce Animal intrusion <24 hrs prior 10,000 1,000 100 10 0 10 20 30 40 50 60 70 80 Age of scat (hrs) prior to irrigation
Minimizing pathogen movement from livestock & wildlife to food and water Livestock production & wildlife Water quality Produce food safety
Microbiological safety of irrigation water
Irrigation water that contacts produce: E. coli 126 MPN / 100 ml (geometric mean n=5) 235 MPN / 100 ml for any single sample
Frequency Proportion E. coli concentrations in California irrigation water, (n=44,000; all seasons: wells, canals, on-farm reservoirs) 100,000 77% Exceedance 100% 10,000 11% 8% 80% 1,000 2% 1% 0.8% 60% 0.5% 0.4% 100 0.1% 40% 10 20% 1 0 1-5 6-25 26-50 51-100 101-200 201-235 236-567 >567 E. coli concentration (MPN/100mL) 0%
Changes in water quality: well compared to reservoir storage E. coli concentrations (MPN/100mL) Seasons Well Reservoir Average Difference % Increase Winter 1.0 18.5 17.5 >1800 Spring 9.8 21.5 11.7 >200 Summer 19.4 77.6 58.2 400 Fall 20.8 65.4 44.6 >300 Overall 13.9 50.6 36.7 >300 25
E. coli O157:H7 in irrigation & surface water, 2008-2010 E. coli O157:H7 % positive WATER produce farm 1/242 0.4% public source 9/316 2.8% SEDIMENT produce farm 1/192 0.5% public source 5/159 3.1%
CCRWQCB From Rincon Creek up to Aptos Creek 23 rivers, creeks or their estuaries April 2009 to April 2010 E. coli O157 6/251 = 2.4% Salmonella 78/251 = 35% 1.3 MPN/100 ml
Fecal coliform and indicator E. coli arithmetic mean (mpn/100 ml) 16,000 14,000 12,000 FC EC 10,000 8,000 6,000 4,000 2,000 0 1 2 3 4 5 6 7 8 9 10 11 12 Month water sample was taken
Bacterial indicators and pathogens for water samples from 23 sites, some of which are listed for a Total Maximum Daily Load in the Central Coast Basin Plan (2008), California 303(d) list of water quality limited segments Bacteria N Average or % Fecal Coliform (MPN/100 ml) TMDL not listed 61 1818 TMDL listed 185 4278 E. coli (MPN/100 ml) TMDL not listed 62 1665 TMDL listed 185 3547 Salmonella (MPN/100 ml) TMDL not listed 63 0.32 TMDL listed 188 0.42 E. coli O157:H7 (present/absent) TMDL not listed 63 1.6 % TMDL listed 188 2.7 %
Salmonella (mpn/100 ml) 10.0 1.0 0.1 1 10 100 1,000 10,000 100,000 1,000,000 Fecal coliforms (mpn/100 ml)
Any questions Livestock production & wildlife Water quality Produce food safety